This study assessed the efficacy and side effects of first trimester medical abortion using mifepristone and vaginally administered misoprostol. Medical abortion was first introduced in Denmark in December 1997, and the acceptability of this new approach in a Danish population was evaluated. The study included the first 100 women seeking medical abortion. The gestational age was from 33 to 56 days. All received 600 mg mifepristone (RU 486) orally followed 2 days later by vaginally administered misoprostol 400 microg. Success was defined as achieving complete abortion without the need for surgical evacuation. Ninety-three percent achieved a successful medical termination of pregnancy. Side effects were few, and the acceptability was high. Ninety percent of the women would prefer medical abortion in case of a new unwanted pregnancy. The combination of mifepristone and vaginally administrated misoprostol is effective, safe, has few side effects and is well accepted by Danish women.